calculateCosts.RdA function that for a given world of possible movement calculates the transition cost for each in terms of a user-defined cost function
calculateCosts(
tiles = NULL,
costFUN = energyCosts,
dir = tempdir(),
costname = deparse(substitute(costFUN)),
...
)A character vector--such as the output to
whichTiles---containing the unique tile IDs for sectors that
should be in the workspace. Default is NULL.
A cost function such as (timeCosts or
energyCosts). The input to such a function should be
a data.table object with column names present in the makeWorld file
(initially c('x_i','x_f','y_i','y_f','z_i','z_f','dz','dl','dr')), and
the output should be an data.table object with the same number of rows and the
desired output variables as the only column names. Constants can be passed in the
... slot. Default is
costFUN = energyCosts
A filepath to the directory being used as the workspace, the same
one instantiated with defineWorld.
Default is tempdir() but unless the analyses will only be performed a few
times it is highly recommended to define a permanent workspace.
whichTiles---containing the unique tile IDs for sectors that
should be in the workspace. Default is NULL.
A name to save the cost call parametrs. Default is the name of the costFUN variable.
Additional parameters to pass to costFUN
An .fst file for each sector named after its sector id
stored in the /World/Diff directory, and/or a data.table object (depending
on the output parameter) containing a data.table with at least eight columns
(1) $from The "x,y"-format coordinates of each possible origin cell
(2) $to The "x,y"-format coordinates of each possible destination cell
(3) $dz The change in elevation between the from and to
cells
(4) $x_i The numeric x coordinate of the origin cell
(5) $y_i The numeric y coordinate of the origin cell
(6) $dl The planimetric distance between the from and to cells
(7) $dr The 3D distance between the from and to cells
(8+) The output cost variables
# Generate a DEM
n <- 5
dem <- expand.grid(list(x = 1:(n * 100),
y = 1:(n * 100))) / 100
dem <- as.data.table(dem)
dem[, z := 250 * exp(-(x - n/2)^2) +
250 * exp(-(y - n/2)^2)]
#> x y z
#> 1: 0.01 0.01 1.0146139
#> 2: 0.02 0.01 1.0404641
#> 3: 0.03 0.01 1.0675194
#> 4: 0.04 0.01 1.0958300
#> 5: 0.05 0.01 1.1254477
#> ---
#> 249996: 4.96 5.00 1.0711366
#> 249997: 4.97 5.00 1.0428260
#> 249998: 4.98 5.00 1.0157707
#> 249999: 4.99 5.00 0.9899205
#> 250000: 5.00 5.00 0.9652271
dem <- rast(dem)
ext(dem) <- c(10000, 20000, 30000, 40000)
crs(dem) <- "+proj=lcc +lat_1=48 +lat_2=33 +lon_0=-100 +datum=WGS84"
# Export it so it doesn't just exist on the memory
dir <- tempdir()
writeRaster(dem, paste0(dir,"/DEM.tif"),overwrite=TRUE)
# Import raster, get the grid
dem <- rast(paste0(dir,"/DEM.tif"))
grid <- makeGrid(dem = dem, nx = n, ny = n, sources = TRUE)
# Select all tiles that exist between x = (12000,16000) and y = (32000,36000)
tiles <- ext(c(12000,16000,32000,36000))
tiles <- as.polygons(tiles)
crs(tiles) <- crs(grid)
tiles <- whichTiles(region = tiles, polys = grid)
# Make a world but limit it to the DEM grid size
defineWorld(source = grid, cut_slope = 0.5,
res = res(dem), dir = dir, overwrite=TRUE)
# Calculate the costs within the world
calculateCosts(tiles = tiles, dir = dir,
m = 70, v_max = 1.5, BMR = 76, k = 3.5, s = 0.05, l_s = 1,
L = 0.8)
#> [1] "Cropping Tile SECTOR_01 (1 of 4)"
#> [1] "Cropping Tile SECTOR_02 (2 of 4)"
#> [1] "Cropping Tile SECTOR_06 (3 of 4)"
#> [1] "Cropping Tile SECTOR_07 (4 of 4)"
#> [1] "Cropping Tile SECTOR_03 (1 of 2)"
#> [1] "Cropping Tile SECTOR_08 (2 of 2)"
#> [1] "Cropping Tile SECTOR_11 (1 of 2)"
#> [1] "Cropping Tile SECTOR_12 (2 of 2)"
#> [1] "Cropping Tile SECTOR_13 (1 of 1)"
#> [1] "Cropping Tile SECTOR_16 (1 of 2)"
#> [1] "Cropping Tile SECTOR_17 (2 of 2)"
#> [1] "Cropping Tile SECTOR_18 (1 of 1)"
#> [1] "Cropping Tile SECTOR_09 (1 of 3)"
#> [1] "Cropping Tile SECTOR_14 (2 of 3)"
#> [1] "Cropping Tile SECTOR_19 (3 of 3)"
#> [1] "Cropping Tile SECTOR_21 (1 of 2)"
#> [1] "Cropping Tile SECTOR_22 (2 of 2)"
#> [1] "Cropping Tile SECTOR_23 (1 of 1)"
#> [1] "Cropping Tile SECTOR_04 (1 of 1)"
#> [1] "Cropping Tile SECTOR_05 (1 of 2)"
#> [1] "Cropping Tile SECTOR_10 (2 of 2)"
#> [1] "Cropping Tile SECTOR_15 (1 of 1)"
#> [1] "Cropping Tile SECTOR_24 (1 of 1)"
#> [1] "Cropping Tile SECTOR_20 (1 of 1)"
#> [1] "Cropping Tile SECTOR_25 (1 of 1)"